This invention relates to digital communication switching systems. More particularly, it is concerned with apparatus for switching time division multiplexed (TDM) signals.
Among the problems present in many known TDM switching systems is the problem of blocking. That is, once a connection between two channels has been established certain other connections are not possible. A non-blocking TDM switching system is described in U.S. Pat. No. 3,678,205 entitled "Modular Switching Network" which issued on July 18, 1972 to Gerald Cohen and Maurice I. Crystal and is assigned to the assignee of the present application. The network described in the application employs a plurality of switching modules, one for each output transmission line. All the incoming data on all the input transmission lines to the network is stored in a data memory in each of the switching modules. Each module also includes a memory for storing connection address information identifying data in the data memory to be transmitted on the output transmission line of the module. The network permits the data present in any channel on any input transmission line to be applied to any channel on any output transmission line through the particular switching module associated with the desired output transmission line. Operation of the switching modules to establish each connection is under the control of a control computer and a timing and control unit.